Control mechanism



Ap 3, 1934. A. H. STRONG CONTROL MEcHANIsM Filed June 1, 11933 l l l,

Patented Apr. 3, 1934 yCONTROL MECHANISM` Archie Hugh Strong,Conshohocken, Pa.

Application June 1, 1933, Serial No. 673,864

Claims.

'I'his invention relates to control mechanism for appliances such aswater heaters employing gas for a heating medium.

One of the primary objects of my invention is the provision of improvedand simplified valve mechanism for controlling the heating medium ofwater heaters and the like employing a pilot, both, by the temperatureof the liquid being heated and by the temperature in the region' of the10 pilot.

Another object of my invention relates to improved valve mechanism'forcontrolling the heating medium of water heaters and the like in whichservice control of the valve is afforded through means responsive to thetemperature of the liquid being heated and safety or emergency controlof the same valve through means responsive to the temperature in theregion of heat application.

A further object resides in providing service and safety control fordevices of the character described with a minimum number of parts.

Still another object of my invention is to provide a combined serviceand safety valve mechanism which is extremely simple and economical tomanufacture and very effective in operation.

How the foregoing, together with such other objects and advantages asmay hereinafter appear or are incident to my invention are realized,

is illustrated in preferred form in the accompanying drawing, wherein-Figure 1 is a fragmentary elevational view illustrating my improvedcontrol mechanism with certain of the parts -appearing in section andwith the casing cover of the mechanism removed;

Figure 2 is a plan section taken on the line 2-2 of Figure 1, and

Figure 3 is a vertical sectiontaken on the line 3 3 of Figure 1.

In Figure 1 the valve control mechanism is indicated as a whole by thereference letter A, and is shown applied to a water heater B, having awater tank or storage vessel 4 and a lower compartment 5 in whicha mainburner 6, such 5 as a gas burner, is located. The supply of heatingmedium or gas to the burner is controlled by a control valve C having agas inlet 7 and a gas outlet 8, 'gas being led from the outlet 8 to theburner 6 by means of al pipe 9. The valve member 10 of the control valveis provided with a valve stem 11 which extends into the casing 12 of thecontrol mechanism A. A suitable seal against leakage at the valve stemis provided which, in this instance, is illustrated in the form of adiaphragm seal 13. The valve 10 is normally urged to its closed positionby means of a spring 14 and is adapted to be moved to its open positionupon actuation of the valve stem 11.

Ignition means for the burner is provided in the form of a pilot l5which may be supported in any suitable manner at a point closelyadjacent to the main burner 6. This pilot receives its gas directly fromthe main gas supply by means of a pipe 16 which, in this instance, isshown connected into the casing of the control valve C at the inlet sidethereof.

The valve control mechanism A comprises in general a supporting casing12 having a removable cover, a valve actuator or snap arm 17, a lever18, which may be termed a compounding lever, a thermostatic device D forcausing actuation of the lever 18, and a safety device E including alever 19 adapted to be operated by a thermostatic device F.

The snap arm 17 is pivotally mounted on a support 20 carried by thecasing l2, the pivot being provided by means of knife-edge portions 21on the snap arm engaging in V-notches 22 in the support 20. This snaparm is resiliently connected to the lever 18 by means of a spring 23connected at its upper end to the upper free end portion of the snap arm17 and at its lower end to the lower free end portion of the lever 18.It is to be noted that the disposition of the lever 18 with respect tothe snap arm 17, and the location of the points of connection of thespring 23 to these members, are such that the snap arm will assume theposition shown in Figure l .when the lever l8'is moved to the `left bythe thermostatic device D, and that it will snap to the position shownin dot and dash lines at 24 when the lever 18 is moved to the right bysaid thermostatic device. The spring connection also serves to hold thesnap arm in proper pivotal relation with the support 20.

With the snap arm 17 in the full-line position the valve 10 is permittedto move to its closed poition but when it snaps over to the positionindicated in dot and dash lines at 24 the lower portion 25 of the snaparm, through its engagement with the valve stem 1l, moves the valve toits open position and thus supplies gas to the burner 6. Actuation ofthe snap arm to the positions just described is accomplished through themedium of the thermostatic device D now to be described.

The thermostatic device D comprises a support 26 adapted to be securedin the wall of the water tank 4 and carrying a tube 27 extending intothe tank. This tube isconstructed of material having a high coefficientof thermal expansion and has located therein a rod 28 constructed ofmaterial having a low coeicient of expansion. The tube 27 is secured tothe support 26 at its end 29 and the rod 28 is secured to the tube at 30as by means of screw threads. This rod extends outwardly through thesupport 26 and into the casing 12 of the control mechanism, and at itsfree or extending end 31 it engages the lever 18 at a point closelyadjacent the pivot 32. It will thus be seen that any movement of the rod28 due to expansion and contraction is greatly compounded because of theconstruction just described and of the length of the lever 18, so thatample movement is provided at the free end of the lever 18 to cause thedesired snap action of the arm 17 with consequent snap opening andclosing of the valve 10. Adjustment of the thermostatic device D maybeprovided by turning the rod 28 to the left or right as by means of anut 33.

The operation of the device as thus far described is as follows. Whenthe water in the tank is cold, the tube 27 contracts, thus moving therod 28 to the right, which, due to its contact with the lever 18 at 31,rocks the lever to the right. This moves the lower end of the spring 23toward the right an amount such that the spring creates a pull on theupper end of the arm 17 in a direction to cause it to snap into theposition shown in dot and dash lines. Such movement of the snap armcauses it to move the valve stem 11 to the left to open the valve 10 andsupply gas to the burner 6 and, assuming that the pilot is lit, thiscauses ignition of the burner.

When the temperature of the water rises to a predetermined value, thetube 27 expands, and since the rod 28 is attached to the tube at itsfree end it moves in a direction away from the lever 18. However, thespring 23 is creating tension on the lever 18 in a direction tending tomove it to the left, and therefore the lever follows the rod 28. Whenthe lever moves in this direction a predetermined amount the arm 17 issnapped into its other position, namely, that shown in full lines, thisbeing due to the shifting of the lower end of the spring to the left.Thus the lower end portion of the snap arm permits the valve 10 to snapinto its closed position to cut oif the supply of gas to the burner.When the water drops to a predetermined low temperature the valve isopened in the manner above described, and so on. The above operation iswhat may be termed the service control of the heater.

Referring now to the thermostatic device F, it will be seen that itcomprises a tube 34 secured at its end 35 in the casing 12, and a rod 36located therein, the construction being similar to that of the tube 27and rod 28 of the thermostatic device D. The rod 36 is secured at itsend 37 in the tube 34wand its free end 38 is adapted to contact with thelever 19 of the safety device E. The lever 19 is pivoted` at 39 in thecasing 12 and is spring pressed in a direction to contact with the rod38. A projection 40 is provided at the lower end portion of the lever19, the amount of projection of which is such that when the lever is inthe position shown in the drawing the snap arm 17 is free to move fromone of its snap positions to the other.

The device F is so positioned that its tube is subjected to heat fromthe pilot 15, and therefore when the pilot is lit the tubeexpands andmoves the rod 38 in a direction away from the lever.

whereby the lever assumes its position of noninterference with the snaparm. However, when the pilot is extinguished the tube 34 cools andcontracts, thus moving the rod 38 in its other direction, whereby thelever 19 is swung to the right on its pivot and the projection 40thereof engages the arm 17 to move it to its full-line position andthereby hold or lock it in the position in which the valve 10 closes tocut oil the supply of gas to the burner 6.

It will thus be seen that in the event the pilot is extinguished whenthe thermostatic device D effects opening of the control valve, thesafety device E actuates the control device in a manner t0 close thecontrol valve and prevent the escape of gas at the burner. Similarly, iffor any reason the thermostatic device F should cool oi to itspredetermined low temperature when the service thermostatic device D iseffecting operation of the control device to hold the valve closed, thenthe safety device E prevents opening of the valve by a change incondition at the thermostatic device D. In either case the control valvewill remain closed until the pilot is again lit, which is the onlyoperation necessary in order to again restore the heater to serviceoperation.

It is to be observed that even through the snap arm may be locked by thesafety device E in its position of maintaining the control valve closed,

the compounding lever 18 is still free to move throughits normal rangedue to its resilient connection rto the snap arm, thus avoiding anystrains on the lever or associated thermostat after actuation of thesafety device.

It will be seen from lthe foregoing that I have provided an improvedcontrol valve mechanism for water heaters and similar appliances inwhich both service control and safety control are afforded with but asingle valve. This is advantageous for the reason that the valve, owingto its being a service valve, is being frequently operated, andtherefore when it is called upon to act as a safety valve it will notstick as might very well be the case if a separate safety valve wereemployed adapted to be actuated only under emergency conditions. Thus byemploying the service valve also as a safety valve, it ispreconditioned, so to speak, to ensure effective operation as a safetyvalve under emergency conditions. The number of parts employed isrelatively few and the arrangement of parts is such as to ensure at alltimes, positive and effective action.

I clainfu-I 1. In a water heater having a main burner, a valvecontrolling the flow of a heating medium to said burner, spring meansnormally tending to close said valve and pilot means for igniting theburner, a thermostatically controlled snap arm engageable with saidvalve to open it and adapted to control spring closing of said valveunder predetermined water temperature conditions, and thermostaticallycontrolled means engaging said snap arm to lock it in the position inwhich the valve is closed under predetermined temperature conditions atthe pilot means.

2. In a water heater having a main burner, a valve controlling the flowof a heating medium to said burner, and pilot means for igniting theburner, a snap arm engageable with said valve toopen it and adapted tocontrol closing of said valve, a thermostat subject to watertemperatures for controlling said snap arm, and a thermostat subject topilot temperatures for controlling said snap arm.

3. In a water heater having a main burner, a

valve controlling the flow oi' a heating medium to said burner, andpilot means for igniting the burner, a snap arm operable on said valveto eieot opening and closing thereof, thermostatically controlled meansengaging said snap arm to efiect such opening and closing underpredetermined Water temperature conditions, and thermostaticallycontrolled means engaging said snap arm to effect closing of the valveunder predetermined temperature conditions at the pilot means.

4. In a water heater having a main burner, a valve controlling the flowof a heating medium to said burner, and pilot means for igniting theburner, an arm operable on said valve to effect snap opening and closingthereof, means for pivoting said arm on a xed part, thermostaticallycontrolled means resiliently connected to said arm to move it topositions eiecting such snap opening and closing of the valve underpredetermined water temperature conditions, and there mostaticallycontrolled means engaging said arm to hold it in its position ofeiecting closing of the valve under predetermined temperature conditionsat the pilot means.

5. In a water heater having a main burner, a valve controlling the oW ofa heating medium to said burner, and pilot means for igniting theburner, an arm pivoted on a fixed part and movable in one direction toeffect opening of Vthe valve and in an opposite direction to controlclosing of the valve, thermostatic means responsive to Watertemperatures for moving said arm in said directions 'and thermostaticmeans responsive to temperatures at the pilot means for holding said armin the position in which the valve is closed when the temperature atsaid pilot means drops to a predetermined low value.

6. In a Water heater having a main burner, a Valve controlling the flowof a heating medium to said burner and pilot means for igniting theburner, the combination of control means for the valve comprising asupport, a valve operating arm, means for pivotally mounting said arm onsaid support, a compounding lever pivotally mounted on said support,spring means connecting the free end portion of said lever to said armto impart snap action to the arm in directions to eiect opening andclosing of the valve when the lever is moved in opposite directions, athermostat responsive to water temperatures in the heater for soactuating said lever whereby the valve is opened and closed inaccordance with changes in water temperature, and thermostaticallyoperated means responsive to changes in temperature at the pilot meansmovable to a position, when said temperature is at a predetermined lowvalue, to engage and hold said arm in its position in which the valve isclosed.

7. In a Water heater having a main burner, a valve controlling the iiowof a heating medium to said burner and pilot means for igniting theburner, the combination of control means for the valve comprising asupport, a valve operating arm, means for pivotally mounting said arm onsaid support, a compounding lever pivotally mounted on said support,spring means connecting the free end portion of said lever to said armto impart snap action to the arm in directions to effect opening andclosing of the valve when the lever is moved in opposite directions, athermostat responsive to water temperatures in the heater for soactuating said lever whereby the valve is opened and closed inaccordance with changes in Water temperature, and thermostaticallyoperated means responsive to changes in temperature at the pilot meansmovable to a position, when said temperature is at a predetermined lowvalue, to lock said arm in its position in which the valve is closed andmovable to a position, when said temperature is at a predeterminedhigher value, to unlock said arm to permit its being moved to its otherposition by the rst mentioned thermostat.

8. In a water heater having a main burner, a valve controlling the iiowof a heating medium to said burner, and a pilot for igniting the burner,means for controlling said valve including a valve actuator pivotallymounted on a xed part, a pair of thermostats for operating saidactuator, one being responsive to Water temperatures in the heater toeiect movement of the actuator to open the valve at predetermined 10WWater temperatures and to eiiect movement of the actuator to cause thevalve to close at predetermined higher Water temperatures, and the otherbeing responsive to pilot temperature to hold the actuator in itsposition of causing the valve to close when the pilot is extinguished.

9. In a Water heater having a burner and a valve controlling the now ofa heating medium to said burner, means for operating said valvecomprising a thermostatically controlled lever, a platelike valveactuating member having a knife edge intermediate of its ends, a fixedsupport having a notch receiving said knife edge to form a pivot forsaid member, said support being located so that one free end portion ofsaid member is in engagement with said valve, and springi meansconnecting the free end of said lever to thI other free end portion ofsaid member, said "spring means being tensioned to hold said valveactuating member in pivoted relation to the support and to snapsaidmember into valve opening and closing positions as said lever isthermostatically operated. y

10. In a water heater having a main burner, a valve controlling the flowof a heating medium to said burner, spring means normally tending toclose said valve, and pilot means for igniting the burner, a pivotedsnap arm, a compound lever resiliently connected to said arm to rock iton its pivot, said arm being so positioned with respect to said valve toactuate the valve to open position when rocked in one direction and tocontrol spring actuation of the valve to closed position when rocked inits other direction, thermostatic means for actuating the compound leverin accordance with water temperature conditions, and thermostaticallycontrolled means engaging the snap arm to lock it in its position inwhich the valve is spring closed under predetermined temperatureconditions at the pilot means.

ARCHIE HUGH STRONG.

